Have all game and application sounds on your iPhone & iPad stopped working all of a sudden for no reason? There is nothing to panic. You don't have to call Apple support right away. There is a good chance that you have accidently turned off the sounds from soft button of your device from control center. This control center comes up when you swipe up from bottom of the screen. Some times you end up doing this accidently. The control center comes up and you end up clicking on volume controls to turn sound off. Just bring up control center again and change volume control settings to fix the issue.
For more information you can look at Use Control Center on your iPhone, iPad, and iPod touch page on Apple's site.